Low-frequency high-voltage sampling circuit

Abstract

The utility model discloses a low-frequency high-voltage sampling circuit, which comprises a differential amplification circuit; the signal input end of the differential amplification circuit is provided with an inverted input circuit and an in-phase input circuit. The inverted input circuit and the in-phase input circuit are connected to the negative electrode and the positive electrode of the differential amplification circuit respectively, and each of the inverted input circuit and the in-phase input circuit comprises a first divider resistor and a second divider resistor which are connected in series; the resistance value of the first divider resistor is smaller than that of the second divider resistor, and the first divider resistor is located at the input end of the second divider resistor; and acceleration capacitors are connected to two ends of the second divider resistor. According to the operational amplifier, the acceleration capacitors are additionally arranged at the output ends of the inverted input circuit and the in-phase input circuit respectively, so that the sampling speed of the operational amplifier is increased, the effect of reducing sampling delay is achieved, and the problem of voltage sampling delay in the prior art is solved.

Description

Technical Field

[0001] The present application relates to a low-frequency and high-voltage sampling circuit, belonging to the technical field of power electronics. Background Art

[0002] According to GB / T 34120-2017 Technical Specifications for Energy Storage Converters of Electrochemical Energy Storage Systems, when a power system fails, if the grid connection point voltage is all within the voltage contour line or above the voltage profile required for low voltage ride-through of the energy storage converter, the energy storage converter should ensure continuous operation without disconnection from the grid; otherwise, the energy storage converter is allowed to be cut out. For energy storage converters that are not cut out during the power system failure, their active power should be able to recover quickly after the fault is cleared, and recover to the value before the fault at a power change rate of at least 30% of the rated power / second from the moment the fault is cleared. In order to make the energy storage converter (PCS) meet the requirements of the national standard low voltage ride-through, the PCS system needs to be able to respond in time when a power grid failure occurs and change according to the changes in the power grid, so as to ensure the safety of the PCS and the power grid and reduce losses. In order to enable the PCS control system to respond and issue commands in a very short time, the high-voltage sampling circuits on the grid side and the inverter side need to have a higher sampling rate. In addition to the slew rate of the op amp itself, the parasitic inductance in the sampling line of the commonly used differential amplifier circuit will also have a certain impact on the sampling rate. Utility Model Content

[0003] In view of this, the present application provides a low-frequency high-voltage sampling circuit to solve the problem of large voltage sampling delay in the above-mentioned prior art. The specific solution is:

[0004] A low-frequency high-voltage sampling circuit comprises: a differential amplifier circuit;

[0005] The signal input end of the differential amplifier circuit is respectively provided with an inverting input circuit and a non-inverting input circuit;

[0006] The inverting input circuit and the non-inverting input circuit are respectively connected to the negative electrode and the positive electrode of the differential amplifier circuit, and the inverting input circuit and the non-inverting input circuit respectively include a first voltage-dividing resistor and a second voltage-dividing resistor connected in series;

[0007] The resistance value of the first voltage-dividing resistor is smaller than the resistance value of the second voltage-dividing resistor, and the first voltage-dividing resistor is located at the input end of the second voltage-dividing resistor;

[0008] The two ends of the second voltage-dividing resistor are connected with an accelerating capacitor.

[0009] Preferably, the first voltage-dividing resistor and the second voltage-dividing resistor are respectively provided in plurality;

[0010] A plurality of the first voltage-dividing resistors and the second voltage-dividing resistors are respectively connected in series.

[0011] Preferably, the total resistance value of a plurality of the first voltage-dividing resistors is equal to the resistance value of a unit of the second voltage-dividing resistor.

[0012] Preferably, the first voltage-dividing resistors are provided in four numbers, and the second voltage-dividing resistors and the accelerating capacitors are provided in five numbers respectively. Preferably, the differential amplification circuit comprises an amplifier;

[0013] The negative electrode of the amplifier is connected to the inverting input circuit, the positive electrode of the amplifier is connected to the non-inverting input circuit, and the output end of the amplifier is connected to a filter.

[0014] Preferably, the positive electrode and negative electrode of the amplifier are respectively provided with a balancing circuit and a feedback circuit; one end of the balancing circuit is connected between the output end of the in-phase input circuit and the positive electrode of the amplifier, and the other end of the balancing circuit is grounded;

[0015] One end of the feedback circuit is connected between the output end of the inverting input circuit and the negative electrode of the amplifier, and the other end of the feedback circuit is connected to the output end of the amplifier;

[0016] Preferably, the positive and negative electrodes of the amplifier are connected to power supply decoupling filter capacitors.

[0017] The beneficial effects of this application include:

[0018] The present application adds acceleration capacitors to the output ends of the inverting input circuit and the non-inverting input circuit respectively, so as to speed up the sampling speed of the operational amplifier and reduce the sampling delay, thereby solving the problem of voltage sampling delay in the prior art.

[0019] The present application splits the first voltage-dividing resistor into multiple series resistors, which increases the creepage distance during normal operation and meets the safety regulations. At the same time, the differential component added without affecting its proportional regulation can improve the response to errors, thereby meeting the energy storage standards for high and low wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the principle of a low-frequency and high-voltage sampling circuit in Embodiment 1 of the present application;

[0021] Figure 2 It is a schematic diagram of the principle of a low-frequency high-voltage sampling circuit in the prior art;

[0022] Figure 3 for Figure 1 The enlarged view of point A in the middle;

[0023] Figure 4 for Figure 1 The enlarged view of point B in the middle;

[0024] Figure 5 for Figure 1 Enlarged view of point C in the middle. DETAILED DESCRIPTION

[0025] A low-frequency high-voltage sampling circuit comprises an input circuit, an amplifier and a filter arranged in sequence along a signal transmission direction;

[0026] The input circuit comprises an inverting input circuit and a non-inverting input circuit arranged in parallel, the input ends of the inverting input circuit and the non-inverting input circuit are connected respectively, and the output ends of the inverting input circuit and the non-inverting input circuit are connected to the negative pole and the positive pole of the amplifier respectively.

[0027] Among them, the inverting input circuit and the non-inverting input circuit both include a plurality of first voltage-dividing resistors connected in series and a plurality of second voltage-dividing resistors connected in series, the input end of the series circuit of the plurality of first voltage-dividing resistors is connected to the output end of the high-voltage signal, the output end of the series circuit of the plurality of first voltage-dividing resistors is connected to the input end of the series circuit of the plurality of second voltage-dividing resistors, and the output end of the series circuit of the plurality of second voltage-dividing resistors is respectively connected to the negative pole and the positive pole of the amplifier; the resistance value of a single first voltage-dividing resistor is smaller than the resistance value of a single second voltage-dividing resistor, and the sum of the resistance values ​​of the plurality of first voltage-dividing resistors connected in series is the same as the resistance value of a single second voltage-dividing resistor, and both ends of the single second voltage-dividing resistor are respectively connected to boost capacitors.

[0028] The output end of the amplifier is connected to a filter;

[0029] A feedback circuit located at one side of the inverting input circuit and a balanced circuit located at one side of the non-inverting input circuit are respectively arranged on both sides of the amplifier; one end of the feedback circuit is connected between the inverting input circuit and the negative pole of the amplifier, and the other end of the feedback circuit is connected between the output end of the amplifier and the filter; one end of the balanced circuit is connected between the non-inverting input circuit and the positive pole of the differential inverting amplifier, and the other end of the balanced circuit is connected to the ground end of the amplifier;

[0030] The positive electrode and the negative electrode of the amplifier are also connected to a power supply decoupling filter capacitor, and the two poles of the power supply decoupling filter capacitor are respectively connected to the positive electrode and the negative electrode of the amplifier.

[0031] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0032] Embodiment 1

[0033] As attached Figure 1 , Attachment Figure 3-5In the low-frequency and high-voltage sampling circuit of the present embodiment shown, V1 is the input end of the inverting input circuit, V2 is the input end of the non-inverting input circuit, and OUT represents the output of the operational amplifier.

[0034] There are 4 first voltage-dividing resistors in the inverting input circuit and the non-inverting input circuit, and 5 second voltage-dividing resistors. The number of acceleration capacitors corresponds to the number of voltage-dividing resistors. The resistance value of a single first voltage-dividing resistor is 250kohms, the resistance value of a single second voltage-dividing resistor is 1Mokms, and the value of the boost capacitor connected across the second voltage-dividing resistor is 470PF.

[0035] In the inverting input circuit, a first voltage-dividing resistor R1, a first voltage-dividing resistor R2, a first voltage-dividing resistor R3, a first voltage-dividing resistor R4, a second voltage-dividing resistor R5, a second voltage-dividing resistor R6, a second voltage-dividing resistor R7, a second voltage-dividing resistor R8 and a second voltage-dividing resistor R9 are connected in series in sequence along the transmission direction of the signal; the two ends of the second voltage-dividing resistor R5, the second voltage-dividing resistor R6, the second voltage-dividing resistor R7, the second voltage-dividing resistor R8 and the second voltage-dividing resistor R9 are respectively connected to a boosting capacitor C1, a boosting capacitor C2, a boosting capacitor C3, a boosting capacitor C4 and a boosting capacitor C5, and the output end of the second voltage-dividing resistor R9 is connected to the negative pole of the amplifier.

[0036] In the in-phase input circuit, a first voltage-dividing resistor R10, a first voltage-dividing resistor R11, a first voltage-dividing resistor R12, a first voltage-dividing resistor R13, a second voltage-dividing resistor R14, a second voltage-dividing resistor R15, a second voltage-dividing resistor R16, a second voltage-dividing resistor R17 and a second voltage-dividing resistor R18 are connected in series in sequence along the transmission direction of the signal, and the output end of the second voltage-dividing resistor R18 is connected to the positive electrode of the amplifier; the two ends of the second voltage-dividing resistor R14, the second voltage-dividing resistor R15, the second voltage-dividing resistor R16, the second voltage-dividing resistor R17 and the second voltage-dividing resistor R18 are respectively connected to a boosting capacitor C6, a boosting capacitor C7, a boosting capacitor C8, a boosting capacitor C9 and a boosting capacitor C10.

[0037] In order to obtain a voltage suitable for the differential amplifier circuit, the output high-voltage signal needs to be voltage-divided. In this embodiment, the first voltage-dividing resistors R1 to R4 and the second voltage-dividing resistors R5 to R10 are sequentially arranged in the inverting input circuit, and the first voltage-dividing resistors R10 to R13 and the second voltage-dividing resistors R14 to R18 are sequentially arranged in the non-inverting input circuit. The output voltages at both ends of V1 and V2 are divided by the resistors to finally obtain an output voltage suitable for operational amplifier processing.

[0038] The voltage suitable for the operational amplifier to process is obtained through the voltage division of each voltage dividing resistor.

[0039] The filter includes a resistor R21 and a capacitor C15, one end of the capacitor C15 is connected to the output end of the resistor R21, and the other end of the capacitor C15 is grounded.

[0040] A feedback circuit and a balancing circuit are respectively arranged on both sides of the amplifier.

[0041] The feedback circuit includes a resistor R19 and a capacitor C11, which are connected in parallel. One end of the parallel circuit of the resistor R19 and the capacitor C11 is connected to the circuit between the output end of the second boost resistor R9 and the negative electrode of the amplifier, and the other end of the parallel circuit of the resistor R19 and the capacitor C11 is connected between the amplifier and the resistor 21.

[0042] The balancing circuit includes a resistor R20 and a capacitor C12, wherein the resistor R20 and the capacitor C12 are connected in parallel, and one end of the parallel circuit of the resistor R20 and the capacitor C12 is connected to the circuit between the output end of the second boosting resistor R18 and the positive pole of the amplifier, and the other end of the parallel circuit of the resistor R20 and the capacitor C12 is connected to the ground terminal of the amplifier.

[0043] The power supply decoupling filter capacitor connected to the two electrodes of the amplifier includes a capacitor C13 and a capacitor C14 connected in series, wherein the capacitor C13 is connected to the positive electrode of the amplifier, the capacitor C14 is connected to the negative electrode of the amplifier, and the capacitor C13 and the capacitor C14 are grounded.

[0044] In this embodiment, the capacitance values ​​of capacitors C13, C14 and C15 are 0.01 u F 。

[0045] The voltages at the two terminals of the amplifier are +15V and -15V.

[0046] The resistance value of R21 is 10ohms.

[0047] The resistance value of R19 and R20 is 50kohms.

[0048] The capacitance value of capacitor C11 and capacitor C12 is 400PF.

[0049] like Figure 2 The figure shows a low-frequency high-voltage sampling circuit of the prior art, wherein the output voltage calculation formula processed by the operational amplifier is shown in formula (1):

[0050] Uout1=50kΩ / (1*6)MΩ*(V2-V1)

[0051] △Uout1=50kΩ / (1*6)MΩ*(△V2-△V1) Formula (1)

[0052] In the present embodiment 1, the acceleration capacitor is respectively provided on the second voltage-dividing resistor, thereby increasing the differential component of the acceleration capacitor in the whole system, and the resistor 1MΩ is split into four 250KΩ series-connected first voltage-dividing resistors, reducing the power consumption of a single resistor, enhancing the stability of the system, and also increasing the creepage distance, so that its safety regulations are not affected. In the present embodiment 1, the output voltage calculation formula processed by the operational amplifier is shown in formula (2):

[0053] Uout2=50kΩ / (6MΩ / / (1 / wc))*(V2-V1)

[0054] △Uout2=50kΩ / (6MΩ / / (1 / △wc))*(△V2-△V1) Formula (2)

[0055] Among them, △w will be very large at the moment of input voltage change, and △Uout2 will also increase with the increase of △w, so △Uout2>△Uout1, which shows that the low-frequency and high-voltage sampling circuit provided in this application can significantly improve the sampling rate.

[0056] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A low-frequency high-voltage sampling circuit, characterized in that: include: Differential amplifier circuit; The signal input end of the differential amplifier circuit is respectively provided with an inverting input circuit and a non-inverting input circuit; The inverting input circuit and the non-inverting input circuit are respectively connected to the negative electrode and the positive electrode of the differential amplifier circuit, and the inverting input circuit and the non-inverting input circuit respectively include a first voltage-dividing resistor and a second voltage-dividing resistor connected in series; The resistance value of the first voltage-dividing resistor is smaller than the resistance value of the second voltage-dividing resistor, and the first voltage-dividing resistor is located at the input end of the second voltage-dividing resistor; The two ends of the second voltage-dividing resistor are connected with an accelerating capacitor.

2. A low-frequency high-voltage sampling circuit according to claim 1, characterized in that: The first voltage-dividing resistor and the second voltage-dividing resistor are respectively provided in plurality; A plurality of the first voltage-dividing resistors and the second voltage-dividing resistors are respectively connected in series.

3. A low-frequency high-voltage sampling circuit according to claim 2, characterized in that: The total resistance value of a plurality of the first voltage-dividing resistors is equal to the resistance value of a unit of the second voltage-dividing resistor.

4. A low-frequency high-voltage sampling circuit according to claim 2, characterized in that: There are four first voltage-dividing resistors, and there are five second voltage-dividing resistors and five acceleration capacitors, respectively.

5. The low-frequency high-voltage sampling circuit according to claim 1, characterized in that: The differential amplifier circuit includes an amplifier; The negative electrode of the amplifier is connected to the inverting input circuit, the positive electrode of the amplifier is connected to the non-inverting input circuit, and the output end of the amplifier is connected to a filter.

6. The low-frequency high-voltage sampling circuit according to claim 5, characterized in that: The positive electrode and the negative electrode of the amplifier are respectively provided with a balancing circuit and a feedback circuit; One end of the balanced circuit is connected between the output end of the in-phase input circuit and the positive electrode of the amplifier, and the other end of the balanced circuit is grounded; One end of the feedback circuit is connected between the output end of the inverting input circuit and the negative electrode of the amplifier, and the other end of the feedback circuit is connected to the output end of the amplifier.

7. The low-frequency high-voltage sampling circuit according to claim 5, characterized in that: The positive and negative electrodes of the amplifier are connected to power supply decoupling filter capacitors.

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